Plate heat exchanger

ABSTRACT

A plate heat exchanger including heat exchanger plates arranged adjacent to each other and in a compressed pack, the heat exchanger plates each having openings aligned with each other and channels configured to receive a heat emitting medium and a heat absorbing medium alternately via the openings. The plate heat exchanger further includes gaskets arranged on a periphery of the openings and between two adjacent heat exchanger plates in gasket regions. The heat exchanger plates have corrugations extending from the openings in a substantially radial direction and uninterrupted through the gasket regions. Corrugations hills and corrugations troughs of adjacent heat exchanger plates cross at crossing points such that adjacent heat exchanger plates support each other at the crossing points. The gasket between the adjacent heat exchanger plates is flanked by the crossing points so that the gasket varies in cross-section to be adapted to a profile of the heat exchanger plates and so that a substantially same gasket pressure is obtained over the extent of the gasket in a compressed condition.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a plate heat exchanger comprisingalternately arranged plates compressed together to a pack, formingclosed channels by means of gaskets arranged between the plates,alternately for a heat emitting and a heat absorbing medium. Thesechannels may be supplied with the respective medium through entry andexit openings in the plates aligned with each other, profiles extendingfrom the entry and exit openings, and in the region of these profiles,gaskets for separating the entry and exit openings, respectively, fromthe heat exchanger surfaces are arranged alternately between pairs ofplates.

2. Discussion of the Background

The gaskets of plate heat exchangers of this type are usually arrangedin flat gasket grooves supporting the gasket laterally. In a known way,the intake and outlet region of the entry and exit openings on the heatexchanger surfaces as such form the weakest points of the gasket. Inthis region, a gasket is arranged only in every second channel while theheat transferring medium encountering the adjacent plate flows in eachinterposed channel, the gasket groove forming an undesired flowresistance. In the region under-flowed in this way, the gasket groovebottom does not obtain a sufficient metallic support. Since it is alsoflat and not embossed in the conventional way, it may deform plasticallyand elastically, locally reducing the gasket pressure. The reducedgasket pressure results in that a leakage may occur in this region evenat lower pressures of the heat exchange medium as well as in otherregions of the gasket.

From the state of the art, structures and measures, respectively, formitigating or reducing the leakiness in the flow region of the entry andexit openings of the plate are known. A known measure consists inpartially enlarging the gasket in this region. However, this possibilityis limited, since a plastic deformation of the gasket groove bottomstill will occur.

Another solution is disclosed in DE-AS-23 09 743. Here a lateral supportof the gasket groove bottom is obtained by a suitable embossment.

The patent document DE 32 39 004 C2 discloses another solution approach.Here the gasket groove bottom is reinforced by additional embossments.

The solution according to GB-PS 1 020 045 goes further than thesolutions mentioned above, in that the embossments of the gasket groovebottom is metallically supported by the respective following plate,however, without adapting the form of the gasket to the embossment. InGB 2 128 726 A, a gasket is also fillingly adapted to the embossment.

With this state of the art, the problem of the tightness in the outletregion of the entry and exit openings is solved in a satisfactorymanner. However, in all these solutions the known gasket groove remainsin its basic form and the advantage of the direct support is tradedagainst a reduction of the flow cross-section for the entering andexiting medium.

SUMMARY OF THE INVENTION

Thus, according to a first aspect of the present invention, the objectof the present invention is to provide a plate heat exchanger of theabove described type, wherein a safe seal is obtained while obviating aconventional gasket groove in the outlet region of the entry and exitopenings of the heat exchanger plates.

According to a second aspect of the present invention, a further objectof the present invention is to provide a plate heat exchanger wherein asafe seal is obtained while obviating a conventional gasket groove inthe peripheral region of the heat exchanger surfaces of the heatexchanger plates.

According to a third aspect of the present invention, a still furtherobject of the present invention is to provide a method of producing aplate heat exchanger wherein the gasket is vulcanized in a vulcanizationpress using a heat exchanger plate as a press mould in the vulcanizationpress.

According to the first aspect of invention, this object is solved bymeans of a plate heat exchanger wherein the profiles extending from theentry and outlet openings are extending in a substantially radialdirection to the heat exchanger surfaces and thereby continuouslytraverse the length of the gasket and cross the corresponding profilesof the adjacent plate, such that the extent of the gasket from thecrossing point of the corrugation hills of one plate with thecorrugation troughs of the other plate is flanked on both sides, wherebythe gasket arranged between the plates has a varying cross-section to beadapted to a corrugation of the plates in this region, so that, incompressed condition, substantially the same specific gasket pressure isobtained over the whole extent of the gasket.

According to the second aspect of invention, this object is solved bymeans of a plate heat exchanger wherein the corrugations of the heatexchanger surfaces extend uninterrupted to the edge of the heatexchanger, the peripheral gasket being arranged between the heatexchanger surfaces, such that the extent of the peripheral gasket isflanked on both sides by the crossing points of the corrugation hills ofone plate with the corrugation troughs of the other plate, theperipheral gasket arranged between the heat exchanger plates varying incross-section to be adapted to the profile of the heat exchangersurfaces in this region.

According to the third aspect of invention, this object is solved bymeans of a method of producing a plate heat exchanger wherein the gasketis vulcanized in a vulcanization press using a heat exchanger plate as apress mould.

Further embodiments of the invention are defined in the accompanyingclaims.

With respect to the prior art, the present invention obviates completelya specific gasket groove and hence a holohedral gasket space. Instead,by a special configuration of the corrugation in the region of theoutlet region of the entry and exit openings and, preferably, in theperipheral region, the gasket is shaped so that the gasket still isflanked laterally, while the tightness is ensured by a special gasketform adapted to this corrugation, the corrugation extending radiallyfrom the entry and exit openings to the heat exchanger surfaces and tothe edge of the heat exchanger surfaces, respectively. Thesecorrugations cross corrugations shaped in the same way of the adjacentplate. The gasket is adapted to the crossing wave-form formed in thisway at both sides, that is the cross-section of the gasket variescorresponding to the profile and is positioned such that, in compressedcondition, substantially the same specific gasket pressure is obtainedover the whole gasket.

Because of the radial configuration of the corrugation the gasket spacetapers from the heat exchanger surfaces on which the medium pressureimpinges to the entry and exit openings and the gasket is wedged by theworking pressure of the medium in this tapered cross-section, whereby itis additionally supported by the crossing points following thereafter.

The claimed invention presents the following advantages over the priorsolutions:

The uninterrupted continuous corrugation in the region of the gasketcauses a high stiffness, whereby the required gasket pressure is ensuredin this region. By obviating the gasket groove chamber an optimized flowchannel is obtained for the underflowing heat exchanging medium andcorresponding small pressure losses. Additionally, by obviating thegasket groove chamber smaller shaping ratios are made possible andthereby a better embossability in the production of heat exchangerplates, thus reducing the cracking risk in the metal shaping.

The uninterrupted corrugations to the edge of the heat exchanger platerender the heat exchanger plate suitable for use in a soldered plateheat exchanger. Thus, the same plates may be used in both a plate heatexchanger of the clamping frame type and of the soldered type reducingthe overall production costs.

Using a heat exchanger plate in a vulcanization press as a press mouldmeans that the gasket is vulcanized directly on the heat exchanger plateresulting in a firm adhesion of the gasket to the heat exchanger plate.

In further embodiments of the invention the radial corrugation extendingfrom the entry and exit openings intersects the gasket at an angle of 50to 80°, preferably of 70°. With this angle of intersection, the positionof the crossing points of the corrugation are determined, on one hand,and the flow passage between the heat exchanger plates in this region isdefined in a flow promoting way, on the other hand. Thereby, thecorrugation of the heat exchanger plates forming a flow passage in thepreferred embodiment (70°) is arranged only at approximately 20° to theflow from the entry and exit openings to the heat exchanger surfaces, sothat the corresponding low pressure losses are obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described hereinafter with reference to anembodiment and with reference to the accompanying drawings, in which:

FIG. 1 is an isometric view of a heat exchanger according to the priorart,

FIG. 2 is a plan view of a heat exchanger plate in accordance with thefirst aspect of the invention, only the top portion of the plate beingillustrated,

FIG. 3 is a detail view of the region III of FIG. 2, with threeindividual exposed, superimposed heat exchange plates and the associatedgasket,

FIG. 4 is a cross-section view corresponding to the view line IV of FIG.3,

FIG. 5 is a perspective view of a gasket adapted to the corrugation.

FIG. 6 is a plan view of a heat exchanger plate in accordance with thesecond aspect of the invention,

FIG. 7 is a detail view of the framed region VII of FIG. 6,

FIG. 8A is a detail view of a heat exchanger plate of FIG. 6 and theassociated gasket,

FIGS. 8B and 8C are enlarged detail views of the encircled areas of FIG.8A,

FIG. 9 is a perspective view of a heat exchanger plate and a cutawayportion of a top press mould of a vulcanization press in accordance withthe third aspect of the invention, and

FIG. 10 is a perspective view similar to FIG. 9 additionally showing alower press mould of the vulcanization press.

DISCUSSION OF THE PREFERRED EMBODIMENTS

In the heat exchanger shown in FIG. 1, for the sake of better overview,only two plates 1, 2 are shown. The clamping plates 4, 14 between whichthe plate pack is compressed, are not yet tightened by the tighteningscrews 5 in the open condition shown. The further parts of the heatexchanger frame are not particular or do not have a bearing on theinvention, respectively.

In the illustration of FIG. 2, enlarged with respect to FIG. 1, of aportion of a heat exchanger plate, the entry and exit openings,respectively, of the heat exchanging medium are designated by 8 and 9.From these openings 8, 9, corrugations extend radially or in a fan-likeway, in the embodiment shown, radially and rotated about 20°, to heatexchanger surface 7 the ridge lines of the corrugation hills of thisprofile being designated by 11. Between the corrugation hills thecorrespondingly formed corrugation troughs are extending.

The heat exchanger plate according to FIG. 2 is shown without a gasketin position, the extent of the gasket 10 being plotted by dotted linesin the region of the opening 9, as an inserted gasket 15 would bepositioned (see FIGS. 3, 4, 5). From this figure it is clearly shownthat, in the outlet region of the entry and exit openings 8, 9, a gasketgroove is completely eliminated and that the profile is continuous overthe extent of the gasket 10. At the circumference of the heat exchangerplate, a gasket groove 6 is provided as is conventional, accommodatingthe peripheral gasket. However, according to the second aspect of theinvention, also the peripheral gasket groove is eliminated, as isdiscussed below.

In the detail view of FIG. 3 a top heat exchanger plate 3 and underlyingheat exchanger plates 2 and 1 are illustrated, in which the underlyingheat exchanger plates are exposed. Between the bottom heat exchangerplate 1 and the intermediate heat exchanger plate 2 the gasket 15 isinserted, while no gasket is provided between the top and intermediateheat exchanger plates. This gap or channel carries flow, the optimalflow conditions being obtained because of the missing gasket groove.

As is clearly seen in FIG. 3, crossing points 12 are obtained betweenthe corrugation hills 11 of the lower heat exchanger plate 1 and thecorrugation troughs of the intermediate heat exchanger plate 2, thecrossing points flanking the gasket 15 on both sides. Only the hills orridges of the corrugations are shown. Also, such crossing points 13 areobtained between the corrugation hills 11 of the intermediate heatexchanger plate 2 and the corrugation troughs of the top heat exchangerplate 3. Because of the uninterrupted extent of the profiles between thesupport points 12 and 13, respectively, the desired stiffness isobtained to apply the gasket pressure on the gasket 15.

The configuration of the gasket 15, over the extent 10 of the gasket, isadapted to the cross-section obtained between the heatexchanger plates,that is also the gasket 15 has corrugation hills 16 and interposedcorrugation troughs, the corrugation hills 16 of the upper surface ofthe gasket crossing the corrugation troughs of the underside of thegasket. This is best shown in FIGS. 4 and 5. Thereby, the gasketcross-section is arranged so that substantially the same gasket pressureexists in a plate pack compressed between the clamping plates 4, 14 ofthe plate heat exchanger.

FIG. 6 illustrates a second embodiment of the present invention whereinthe corrugations 17 of the heat exchanger surfaces 7 extenduninterrupted to the edge 18 of the heat exchanger plate. Only some ofthe corrugations are shown in the figure while it is understood that thewhole heat exchanger plate is covered by corrugations. The corrugationsmay be of the same shape as in the previous figures. The invention isequally applicable to any shape of the corrugations.

FIG. 7 is a detail view of the framed region VII of FIG. 6. As is shownin FIG. 7, the edge 18 of the heat exchanger plate is provided with aflange 21. In a plate heat exchanger of the clamping plate type as isshown in FIG. 1, the flange has no significant function but adds to thestability and integrity of the plate heat exchanger. However, in a plateheat exchanger of the soldered type, that is the heat exchanger platesare soldered together without the need of any gasket, the flange 21 isused to provide a further surface for the soldering in addition to thesoldering at the crossing points between the heat exchanger surfaces.

FIG. 8A is a detail view of a heat exchanger plate with the associatedgasket 15, 19 placed on the heat exchanger plate 2. As is shown in FIGS.8B and 8C similar to FIG. 3, the gasket is positioned between anintermediate plate (the broken lines depcting the hills) and a top plate(the solid lines depicting the troughs). In the region shown in FIG. 8C,the peripheral gasket 19 has a cross section corresponding to that shownin FIG. 4, but with parallel corrugations.

The corrugation of the heat exchanger surfaces (7) may intersect theperipheral gasket (19) at an angle in the range of approximately 40° to70°. A small intersection angle results in a small pressure drop butlower efficiency of the heat exchanger, while a greater intersectionangle results in a large pressure drop but greater efficiency of theheat exchanger. Thus, the angle is selected in accordance with theapplication of the heat exchanger.

It is preferred that the gasket is vulcanized in order to obtain thedesired strength. In accordance with the third aspect of the presentinvention, the vulcanization is effected by means of a vulcanizationpress using the heat exchanger plate itself as one of the press moulds.This results in that the gasket is adhered firmly to the heat exchangerplate through the vulcanization process.

In FIG. 9, a portion of a top press mould 23 is shown together with aheat exchanger plate 22. For the sake of better clarity in the drawings,the gasket and the rest of the vulcanization press are omitted. For thesame reason, the corrugations around the exit and entry openings aresimplified, while it is understood that any form of corrugations may beused. It will be appreciated by persons skilled in the art that thegasket is placed between the press mould 23 and the heat exchanger plate22 which are then compressed and subjected to a conventionalvulcanization treatment.

In FIG. 10 a further advantageous development is shown. In thisembodiment, the vulcanization press comprises two press moulds 23belonging to the vulcanization press proper and one heat exchanger plate22. Thus, two gaskets are placed over and under, respectively, the heatexchanger plate 22 and are vulcanized at the same time. As is known,every second plate in a plate heat exchanger is provided with a gasketon both sides, while the other plates have no gaskets.

The adhesion of the gasket to the heat exchanger plate may be enhancedeven further by providing perforations over the extent of the gasket,that is holes are provided in the plates with a suitable spacing. InFIG. 8C, two holes 20 are shown. Thus, when two gaskets are vulcanizedin a vulcanization press as shown in FIG. 10 at the same time, they arebonded together through the perforations 20 resulting in a very strongbinding of the gaskets together and to the heat exchanger plate.

We claim:
 1. A plate heat exchanger comprising:heat exchanger platesarranged adjacent to each other and in a compressed pack, the heatexchanger plates each having openings aligned from one heat exchangerplate to another heat exchanger plate so as to define channelsconfigured to receive a heat emitting medium and a heat absorbing mediumalternately in said channels via said openings; and gaskets arranged ingasket regions on a periphery of said openings and between the one heatexchanger plate and the another heat exchanger plate wherein;the heatexchanger plates have corrugations extending from the openings in asubstantially radial direction and uninterrupted through the gasketregions, hills and troughs of the one heat exchanger plate and theanother heat exchanger plate cross at crossing points such that said oneheat exchanger plate and said another heat exchanger plate support eachother at the crossing points, each gasket is flanked by the crossingpoints, each gasket is arranged between said at least two adjacent heatexchanger plates and varies in cross-section so as to be adapted to aprofile of the heat exchanger plates, and a substantially same gasketpressure is obtained over an extent of each gasket in a compressedcondition.
 2. A plate heat exchanger according to claim 1, wherein thecorrugations of the heat exchanger plates extend uninterrupted to anedge of the heat exchanger plates.
 3. A plate heat exchanger accordingto claim 2, wherein the corrugation of the heat exchanger platesintersect the gaskets at an angle in an inclusive range of 40° through70°.
 4. A plate heat exchanger according to claim 3, wherein the gasketscomprise vulcanized in situ gaskets.
 5. A plate heat exchanger accordingto claim 4, wherein the heat exchanger plates define perforationslocated in the gasket regions and two gaskets are vulcanized togetherthrough the perforations.
 6. A plate heat exchanger according to claim5, wherein the heat exchanger plates comprise flanges.
 7. A plate heatexchanger according to claim 4, wherein the heat exchanger platescomprise flanges.
 8. A plate heat exchanger according to claim 3,wherein the heat exchanger plates comprise flanges.
 9. A plate heatexchanger according to claim 2, wherein the heat exchanger platescomprise flanges.
 10. A plate heat exchanger according to claim 1,wherein the heat exchanger plates comprise flanges.
 11. A method ofproducing a plate heat exchanger comprising steps of:forming openings inheat exchanger plates: forming corrugations on said heat exchangerplates, said corrugation extending from the openings in a substantiallyradial direction uninterrupted through gaskets regions located on aperiphery of said openings; and vulcanizing gaskets in a vulcanizationpress and positioning said gaskets in said gasket regions and betweenadjacent heat exchanger plates, said vulcanizing step includes pressingsaid gasket with at least one of said heat exchanger plates.
 12. Amethod according to claim 11, wherein said pressing step comprisespressing with a heat exchanger plate as an intermediate press moldbetween two gaskets to be vulcanized and two press molds of thevulcanization press.
 13. A method according to claim 12, furthercomprising perforating the heat exchanger plates in the gasket regions.14. A method according to claim 13, wherein said vulcanizing stepcomprises vulcanizing two gaskets through perforations.
 15. A methodaccording to claim 11, wherein said step of forming corrugationscomprises forming corrugations uninterrupted to an edge of the heatexchanger plates.
 16. A method according to claim 11, wherein said stepof forming corrugations comprises forming corrugations at an angle withsaid gaskets, said angle being in an inclusive range of 40° through 70°.17. A method according to claim 11, wherein said vulcanizing stepcomprises vulcanizing the gaskets in situ.
 18. A method according toclaim 11, further comprising forming flanges on said heat exchangerplates.
 19. A plate heat exchanger according to claim 1, wherein thecorrugations intersect the gaskets at an angle in an inclusive range of50° through 80°.